Genes increase lung cancer risk
SMOKING: Risks could be down to your genes
The finding shows that some people have an inherited susceptibility to the cancer, which makes them more vulnerable to the damaging effects of tobacco.
The genetic variations are widespread, affecting up to half the population, and increase the risk of lung cancer in smokers by up to 80pc.
But scientists stressed that the discovery did not amount to a “licence to smoke” for people free of the genetic variants. The risk of lung cancer remains high in all smokers, regardless of their genetic make-up.
The finding could allow stop-smoking services to be targeted at those at highest risk, who have a one-in-four chance of developing lung cancer. Those without the gene variants who smoke have a one-in-seven chance.
Three separate research groups – in Britain, France and Iceland – independently reached the same conclusion. More than one million cases of lung cancer are diagnosed each year. Smokers are 26 times more likely to develop the disease than non-smokers.
VARIANTS
By comparing the frequency of more than 300,000 gene variants in thousands of lung cancer patients, the three research groups narrowed the search down to two genetic variants on chromosome 15.
Smokers with one copy of the two variants – present in half the population – have a 30pc increased risk of lung cancer, and those with two copies – one in 10 of the population – have an 80pc increased risk, compared with smokers without the variants.
In non-smokers, in whom the risk of lung cancer is less than 1pc, the presence or absence of the gene variants appears to make no difference, implying that the genes are switched on by nicotine or other constituents of tobacco smoke.
Paul Brennan, of the International Agency for Research on Cancer in Lyons, France, who led one of the studies, said: “What is important for the individual is the absolute risk of getting lung cancer. If you smoke all your life it is about 15 per cent, and if you have no copies of the gene variants it will be a bit less.”
